Closing unit of a shaping machine

ABSTRACT

A closing unit of a shaping machine includes a moveable clamping plate, a push rod connected to the moveable clamping plate and having an outside profile, a divided locking nut provided with an inside profile, and a closing force mechanism for acting on the moveable mold clamping plate with a closing force. The push rod is lockable in a closed position of the locking nut by the cooperation of the inside profile and the outside profile with the closing force mechanism. For displacement of the locking nut between an opened and the closed position, a rotary drive is provided for rotation of a shaft, and at least one toothed rack cooperates with the shaft by way of a tooth arrangement and is connected to the locking nut.

The present invention concerns a closing unit of a shaping machinehaving the features of the classifying portion of claim 1.

Closing units of the general kind set forth have a moveable clampingplate, a push rod connected to the moveable mounting plate and having anoutside profile, a divided locking nut provided with an inside profile,and a closing force mechanism for acting on the moveable mold clampingplate with a closing force.

In that arrangement, in the closed position of the locking nut, the pushrod is locked by the cooperation of the inside profile and the outsideprofile with the closing force mechanism.

A closing unit of the general kind set forth is disclosed for example inAT 13625 U1. In that case the nut halves are displaced by means ofeccentrics fixed to a driven shaft. What is capable of improvementtherein is that the shaft and consequently the drive must be orientedparallel to the longitudinal axis of the push rod in order to avoidasymmetrical application of force (gives rise to a risk of jamming) tothe divided nut. The structural length of the closing unit is increasedas a result. If the attempt is made to orient the drive transversely bymeans of a direction-changing transmission then the number of moveableparts is inevitably increased and the unavoidable play in thetransmission reduces the accuracy of open-loop or closed-loop control ofthe movement of the nut halves.

Closing units having four beam members are not of the general kind setforth. In that case the beam members are not locked relatively to theclosing force mechanism but relatively to the moveable mold clampingplate. Because of the greater number of beam members and the fact thatthe locking means in this case are arranged at the end of the closingunit, the space situation here is completely different.

The object of the invention is to provide a closing unit which is of ashorter structure in comparison with the state of the art.

That object is attained by a dosing unit having the features of theclassifying portion of claim 1.

That is achieved in that to displace the locking nut between an openedand the closed position, there is provided a rotary drive for rotating ashaft and at least one toothed rack which cooperates by way of a tootharrangement with the shaft and which is connected to the locking nut.

By virtue of the use of toothed racks it is particularly easily possiblefor the orientation of the shaft or the rotary drive to be freelyselected. As a result the closing unit can be shorter.

A further advantage lies in the low number of moveable parts and as aconsequence thereof longer maintenance intervals for the closing unit.

Further advantageous embodiments of the invention are defined in theappendant claims.

The tooth arrangement can be of a particularly simple configurationinsofar as there is provided a gear which is fixed to the shaft andwhich is motionally coupled to the at least one toothed rack by way ofthe tooth arrangement.

It can also be conducive to a simple construction to provide preciselytwo toothed racks cooperating with the shaft and connected to thelocking nut. In that respect it is particularly advantageously possibleto use each side of the gear, in which case naturally an oppositelydisposed movement is produced. That opposite movement is necessary toopen the locking nut as nut halves must be moved in oppositerelationship for opening and closing.

Then each toothed rack can be connected to a nut half, which, asmentioned, represents a particularly simple construction.

It can preferably be provided that the rotary drive is in the form of anelectric drive—in particular a servo motor. Electric drives, inparticular servo motors, are particularly accurate in terms ofclosed-loop or open-loop control and are therefore highly suited fordriving the nut halves.

Furthermore it can serve for structural simplicity if there is provideda bypass element for bypassing the push rod for connecting the at leastone toothed rack to the locking nut. In that respect it can particularlypreferably be provided that the bypass element is in the form of abridge connected to the at least one toothed rack and, two bars whichare connected to the bridge and the locking nut.

The bypass element, in particular the bars, can in that case serve, as aguide for that half of the locking nut, to which the bypass element (inparticular the bars) is not connected. In that way it is possible toprovide for guidance of the nut halves, with a very low level ofstructural complication and expenditure.

The effect of the invention of reducing the structural length of theclosing unit can be optimized by the shaft being arranged in a planewhich is disposed substantially perpendicular to an axis of the push rodand/or by the shaft being arranged substantially horizontally.

The at least one toothed rack can be arranged substantially vertically.

To counteract the wear or a worsening in the tooth coupling between theshaft and the at least one toothed rack it is possible to provide ahousing in which the tooth arrangement is disposed. That can beparticularly effective if the housing is at least partially filled witha lubricant and has at least one seal to prevent loss of the lubricant.

The closing unit can preferably be hydraulic.

The closing unit can preferably have precisely one push rod.

Protection is also claimed for a shaping machine having a closing unitaccording to the invention.

Further advantages and details of the invention will be apparent fromthe Figures and the related specific description. In the Figures:

FIG. 1 shows a divided nut according to the invention with toothed rackdrive in the closed position,

FIG. 2 shows a divided nut according to the invention with toothed rackdrive in the opened position,

FIG. 3 shows a second embodiment of a divided nut according to theinvention with toothed rack drive in the closed position,

FIG. 4 shows a second embodiment of a divided nut according to theinvention with toothed rack drive in the opened position, and

FIG. 5 shows a sectional view of a closing unit according to theinvention.

FIG. 1 shows a divided nut 6, the halves 13 of which are respectivelyconnected to a toothed rack 11. The toothed racks 11 are driven by wayof a tooth arrangement 8 with the gear 12 by the shaft 10. In this casethe shaft 10 is rotated by the servo motor 9. It is to be noted that thehalf 13 of the locking nut 6, that is the lower half in the Figure, isconnected to the corresponding toothed rack 11 by way of a bypasselement 14. That bypass element 14 substantially comprises a bridge 15and two bars 16. The bars 16 are guided portion-wise by the half 13 ofthe locking nut 6, that is the upper half in the Figure. That providesadditional guidance for the upper half 13 of the locking nut 6. The gear12 which cooperates with the toothed racks 11 by way of the tootharrangement 8 is disposed in a housing 17. That housing 17 is fixed to acollar 19. The collar 19 is connected to the piston portion 23 of aclosing force cylinder or is fixed thereto (see also FIG. 5).

In addition, connected to the collar 19 is a guide 18 cooperating withgrooves on the nut halves 13.

FIG. 2 shows the embodiment in FIG. 1, with the divided locking nut 6opened.

FIGS. 3 and 4 show a further embodiment of the invention (views similarto FIGS. 1 and 2). In this case the tooth arrangements do not extendover the entire length of the toothed racks 11. That permits the housing17 to be of a sealed configuration, whereby the tooth arrangement 8 canrun in oil.

The housing 17 is therefore filled with lubricant—in this case oil—andis sealed off by means of the seals 24 to prevent lubricant loss. Byvirtue of the fact that the toothed racks 11 run in oil wear is reducedand fouling matter does have any access.

FIG. 5 shows the divided nut 6 according to the invention in a closingunit which in this case is hydraulic.

The collar 19 is connected to the piston portion 23 of the closing forcecylinder or is fixed thereto. A closing force is exerted on the pistonportion 23 of the dosing force cylinder by acting on a chamber 21 with ahydraulic fluid (generally oil). In this arrangement a cylinder portion22 of the dosing force cylinder is fixedly connected to a machine frame4 (or an end plate), When the divided nut 6 is locked the closing forcecan be transmitted from the piston portion 23 of the closing forcecylinder to the two halves 13 of the locking nut 6 and further by way ofthe inside profile 5 to the outside profile 7 of a push rod 3. The pushrod 3 is connected to the moveable clamping plate 2. In that way theclosing force can be transmitted to a mold tool of which one half isfixed to the moveable clamping plate 2.

1. A closing unit of a shaping machine comprising: a moveable clampingplate, a push rod connected to the moveable clamping plate and having anoutside profile, a divided locking nut provided with an inside profile,and a closing force mechanism for acting on the moveable mold clampingplate with a closing force, wherein the push rod is lockable in a closedposition of the locking nut by the cooperation of the inside profile andthe outside profile with the closing force mechanism, wherein fordisplacement of the locking nut between an opened and the closedposition there is provided a rotary drive for rotation of a shaft and atleast one toothed rack, which cooperates with the shaft by way of atooth arrangement and which is connected to the locking nut.
 2. Theclosing unit as set forth in claim 1, wherein there is provided a gearwhich is fixed to the shaft and which is motionally coupled to the atleast one toothed rack by way of the tooth arrangement.
 3. The closingunit as set forth in claim 1, wherein there are provided precisely twotoothed racks cooperating with the shaft and connected to the lockingnut.
 4. The closing unit as set forth in claim 1, wherein the dividedlocking nut has two halves, each half preferably being connected to atoothed rack.
 5. The closing unit as set forth in claim 1, wherein therotary drive is in the form of an electric drive—in particular a servomotor.
 6. The closing unit as set forth in claim 1, wherein there isprovided a bypass element for bypassing the push rod for connecting theat least one toothed rack to the locking nut.
 7. The closing unit as setforth in claim 6, wherein the bypass element is in the form of a bridgeconnected to the at least one toothed rack and two bars which areconnected to the bridge and the locking nut.
 8. The closing unit as setforth in claim 4 and having a bypass element for bypassing the push rodfor connecting the at least one toothed rack to the locking nut, whereinthe bypass element in particular the bars serves as a guide for thathalf of the locking nut, to which the bypass element—in particular thebars—is not connected.
 9. The closing unit as set forth in claim 1,wherein the shaft is arranged in a plane which is disposed substantiallyperpendicular to an axis of the push rod.
 10. The closing unit as setforth claim 1, wherein the shaft is arranged substantially horizontally.11. The closing unit as set forth in claim 1, wherein the at least onetoothed rack is arranged substantially vertically.
 12. The closing unitas set forth in claim 1, wherein there is provided a housing in whichthe tooth arrangement is arranged.
 13. The closing unit as set forth inclaim 12, wherein the housing is at least partially filled with alubricant and has at least one seal to prevent loss of the lubricant.14. A shaping machine having a closing unit as set forth in claim 1.